British politician and social reformer who dedicated himself to achieving greater safety for seamen and whose name has been given to a line on the side of a ship, indicating the maximum depth to which that ship may be legally loaded. He first entered the House of Commons as a Liberal in 1868. In 1873 he published Our Seamen, a powerful attack on “coffin ships,” unseaworthy and overloaded vessels, often heavily insured, in which owners risked their crews' lives. Plimsoll initiated an investigation by a royal commission in 1873, and in 1876 the Merchant Shipping Act gave stringent powers of inspection to the Board of Trade and fixed the loading line (Plimsoll mark (Plimsoll line)) for ships. In 1887 he became president of the National Amalgamated Sailors' and Firemen's Union and raised a further agitation about the horrors of cattle ships.